Re: [MW:5811] MPI vs DPI

Amir,

in general fabrication of mild steel, there is no reason why DPI can not
be used. It is actually a common enough practice ( you would rarely walk
into any fabrication shop without seeing some cans lying around). I'm
assuming the purpose is just for a general overview of weld quality such
as fillet welds and not as a substitute for penetration butt welds. MPI
& DPI in this instance perform the same basic function, and that is the
detection of surface defects.

Don't get confused by claims that MPI can detect subsurface - it can -
but interpretation is difficult and also subjective. If you are looking
for subsurface defects you use Radiographic or ultrasonic testing.

hope this helps

Declan

On 30/06/2010 13:14, Amir Zakee Adnal wrote:
> Declan
> We are doing some fabrication on normal carbon steel but we don't have
> the MPI set at this moment. My client would like to have some NDT
> tested. I need to convince my client that DPI is good enough to get
> the fabrication tested.
>
> Regards,
> Amir Zakee
>
> On 6/30/10, Declan Foley<declan1foley@eircom.net> wrote:
>
>>
>> MPI is for ferromagnetic materials only. It is supposedly useful for
>> defects of depth 6mm, but ask anyone who performs the tests and they
>> will tell you it is not!
>>
>> DPI can be conducted on any material. It is not recommended on materials
>> that have porous surfaces such as castings and the like.
>>
>> Strictly speaking they are both considered surface tests. As regards
>> substituting one for the other, I have never come across any situation
>> where you couldn't. What are you testing?
>>
>> Declan
>>
>> On 29/06/2010 17:35, mohammed helal wrote:
>>
>>> The major difference is the DPI is only for the defects that open to
>>> the surface and the MPI for the subsurface defect ( 6 mm deep).
>>>
>>> Eng.MOHAMMED ABD EL-AZIM HILAL
>>> MECHANICAL ENGINEER
>>> CSWIP 3.1 - NDT (RT- MT - PT)
>>> OTISHAN CONSULTANT ENGINEER
>>> 00966-502612218 - 0020103124557
>>>
>>>
>>> --- On *Tue, 6/29/10, george.dilintas@gr.bureauveritas.com
>>> /<george.dilintas@gr.bureauveritas.com>/* wrote:
>>>
>>>
>>> From: george.dilintas@gr.bureauveritas.com
>>> <george.dilintas@gr.bureauveritas.com>
>>> Subject: Re: [MW:5791] MPI vs DPI
>>> To: "materials-welding"<materials-welding@googlegroups.com>
>>> Date: Tuesday, June 29, 2010, 7:06 PM
>>>
>>> Mpi can be used only on ferromagnetic materials
>>>
>>>
>>> ----- Original Message -----
>>> From: Amir Zakee Adnal [amirzakee@gmail.com
>>> <http://us.mc1138.mail.yahoo.com/mc/compose?to=amirzakee@gmail.com>]
>>> Sent: 29/06/2010 16:52 ZE5
>>> To: materials-welding@googlegroups.com
>>>
>>> <http://us.mc1138.mail.yahoo.com/mc/compose?to=materials-welding@googlegroups.com>
>>> Subject: [MW:5787] MPI vs DPI
>>>
>>>
>>>
>>> Dear all
>>> What is/are major difference between MPI and DPI? Can MPI be
>>> substitute with DPI? Is there any code or standard that allow such
>>> substitution?
>>>
>>> Regards,
>>> Amir Zakee
>>>
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>> --
>> To post to this group, send email to materials-welding@googlegroups.com
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>> The views expressed/exchnaged in this group are members personel views and
>> meant for educational purposes only, Users must take their own decisions
>> w.r.t. applicable code/standard/contract documents.
>>
>>
>

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